Solar collector and cooling system having the same

ABSTRACT

A solar air conditioning system and method of superheating working fluid is provided. The solar air conditioning system superheats the working fluid using radiant energy from the sun, and then delivers the working fluid as a superheated and higher-pressured gas to a condenser within the solar air conditioning system. The solar air conditioning system includes a solar collector within which the working fluid is superheated.

This application is a continuation of pending U.S. patent applicationSer. No. 12/926,380, filed Nov. 15, 2010, which is incorporated hereinby reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Apparatuses and methods consistent with the present invention relate tosuperheating working fluid and delivering the superheated working fluidto a condenser of an air conditioning system, and more particularly, tousing solar energy to superheat the working fluid prior to delivery tothe condenser.

2. Description of the Related Art

Air conditioning systems on the market today use a compressor tocompress a working fluid such as a refrigerant, packing the molecules ofthe working fluid closer together thus raising the energy andtemperature of the working fluid. As shown in the related art airconditioning system (100) of FIG. 1, working fluid arrives at thecompressor (101) as a cool, low-pressure gas. The compressor (101) ispowered by electricity to mechanically squeeze the working fluid, andthe squeezing results in packing the molecules of the working fluidcloser together. The closer the molecules of the working fluid aretogether, the higher the working fluid's energy and temperature.

After compression, the working fluid leaves the compressor (101) as ahot, high-pressure gas and flows into a condenser (102). The gas entersthe condenser (102) and begins cooling and changing back into a liquidat the bottom one-third of the coils of the condenser (102). When theworking fluid leaves the condenser (102) as a semi liquid, itstemperature is much cooler and its state has changed from a gas to asemi-liquid under high pressure. This semi-liquid is sent into anevaporator (104) through a metering device (103) that controls thedispensing rate of the semi-liquid working fluid to the evaporator(104). Within the evaporator (104), the semi-liquid's pressure drops andthe semi-liquid begins to evaporate into a gas. As the semi-liquidchanges to gas and evaporates, heat is extracted from the surroundingair. This heat is needed for separating the molecules of the workingfluid in its transformation of state from semi-liquid to gas. By thetime the working fluid leaves the evaporator (104), it is a cool,low-pressure gas. The working fluid then returns to the compressor (101)as the cool, low-pressure gas to begin this cycle all over again.

In the air conditioning system of FIG. 1, a fan (not shown) is used todischarge the hot air emanating from the coils of the condenser (102) tothe outside, while cold air emanating from the coils of the evaporator(104) is blown into the space to be cooled.

Low temperature, low-pressure refrigerant as the working fluid isdelivered to the compressor (101). Different refrigerants have differenttemperature points and characteristics when used in the related art airconditioning system (100). The related art air conditioning system (100)uses the compressor (101) to increase the pressure on the gaseous stateworking fluid, thus also heating the working fluid, and sends the heatedworking fluid to the condenser (102) where the working fluid becomes asemi-liquid after traveling through the coils of the condenser (102). Asshown in FIG. 2, the working fluid in a hot, high-pressure gaseous stateis forced into the top of the coils of the condenser (102) (i.e., thecondenser/condensing coil) located outside. Air blowing across the coilscondenses the working fluid from the gas into a semi-liquid state and inthis conversion from gas to semi-liquid, heat is released into theoutside air.

The change of state of the working fluid from gas to semi-liquidtypically starts to occur approximately two-thirds of the way down thecoils of the condenser (102). Thus, the related art air conditioningsystem (100) only changes a portion of the gas into a liquid state, sothe working fluid is actually in the form of a saturated vapor(semi-liquid) when the working fluid enters into the metering device(103). The working fluid is delivered to the metering device (103) as asaturated vapor.

Although the size of the condenser (102) in the related art airconditioning system (100) may be increased in order to increase thepressure and temperature of the working fluid when compressed, it is notpractical to use a super compressor or even an oversized condenser coildue to the expenditure of an excessive amount of electricity, highequipment cost and undesirable equipment size.

As shown in FIG. 3, the working fluid enters the metering device (103)and is sent to the evaporator (104) in a cold, semi-liquid state. Warmair from inside the house boils and vaporizes the cold working fluid andits state changes into a gas. When the working fluid boils, a lot ofheat is absorbed in the process. This is called the latent heat ofvaporization and makes for very efficient heat transfer. The workingfluid is a good material for use in heat transfer due to its property ofbeing a gas at atmospheric pressure, its ability to absorb a lot of heatwhen it boils and giving off a lot of heat when it condenses. The warmair from inside the house is drawn into and passed through the coils ofthe evaporator (104) where it cools, and the cooler air is then sentback into the house. As such, the evaporating of the semi-liquid stateworking fluid at a very low boiling point results in the removal of theheat from the warm air inside the house.

The related art air conditioning system (100) is designed to change onlya relatively small portion of the gaseous state working fluid into theliquid state so that when the working fluid enters into the meteringdevice (103) the working fluid is in the state of a saturated vapor(semi-liquid). In this related art air conditioning system (100), thecompressor (101) is relied upon to deliver a volume of working fluid tothe condenser (102) as a saturated vapor under high pressure. The volumeof the working fluid in the related art air conditioning system (100)affects the capacity of the system for heat removal. The temperature andthe pressure of the gaseous state working fluid entering the condenser(102) have a direct bearing on the characteristics of the working fluidat the output of the condenser (102), in that the hotter andhigher-pressured the gas is at the input of the condenser (102), thecolder and more transformed to liquid is the working fluid leaving thecondenser (102). More specifically, the hotter the gas at the input ofthe condenser (102), the higher the percentage of gas being changed intoliquid under high pressure.

However, the compressor (101) of the related art air conditioning system(100) is limited by the amount of pressurization that it can practicallyprovide. As such, due to the limit on the provided pressure, thetemperature of the working fluid exiting the compressor (101) is alsolimited to a relatively cool temperature.

SUMMARY OF THE INVENTION

Exemplary embodiments of the present invention overcome the abovedisadvantages and other disadvantages not described above. Also, thepresent invention is not required to overcome the disadvantagesdescribed above, and an exemplary embodiment of the present inventionmay not overcome any of the problems described above.

Aspects of the present invention relate to a solar air conditioningsystem that superheats a working fluid. According to an aspect of thepresent invention, the working fluid is delivered as a superheated andhigher-pressured gas to a condenser within the solar air conditioningsystem.

According to another aspect of the present invention, the working fluidis superheated using radiant energy from the sun, and then delivereddirectly to the condenser.

According to another aspect of the invention, the working fluid issuperheated using a solar collector. The solar collector may beconstructed using at least one evacuated tube.

According to an exemplary embodiment of the present invention, there isprovided a solar air conditioning system that includes a compressor, asolar collector, a condenser, and an evaporator.

According to another exemplary embodiment of the present invention,there is provided a solar air conditioning system that includes acompressor that compresses a working fluid, a solar collector coupled tothe compressor, the solar collector heating the compressed workingfluid, a condenser coupled to the solar collector, the condensercondensing the heated working fluid, and an evaporator coupled betweenthe condenser and the compressor, the evaporator evaporating thecondensed working fluid.

According to another exemplary embodiment of the present invention, thesolar collector includes at least one evacuated tube that heats thecompressed working fluid, wherein, the compressed working fluid isheated while flowing within an interior space of the at least oneevacuated tube.

According to another exemplary embodiment of the present invention, theat least one evacuated tube receives radiant energy from the sun,generates heat from the radiant energy, and transfers the heat through aheat transfer fluid to the compressed working fluid flowing within theinterior space of the at least one evacuated tube.

According to another exemplary embodiment of the present invention, aproper charge of the solar air conditioning system is obtained when apressure P of the working fluid is balanced in accordance with the idealgas law, PV=nRT, in which V is a volume of a sealed space within whichthe working fluid circulates, n is an amount of the working fluidpresent within the solar air conditioning system, R is the universal gasconstant, and T is a temperature of the working fluid.

According to another exemplary embodiment of the present invention,there is provided a solar collector that includes an inlet pipe thatreceives a working fluid, at least one u-tube that receives at a firstend the working fluid from the inlet pipe, an outlet pipe that receivesthe working fluid from a second end of the at least one u-tube, and atleast one evacuated tube that heats the working fluid, wherein theworking fluid is heated while flowing within an interior space of the atleast one evacuated tube, and wherein the at least one u-tube isconfigured to extend within the interior space of the at least oneevacuated tube.

According to another exemplary embodiment of the present invention, theinterior space of the at least one evacuated tube is filled with a heattransfer fluid and the at least one u-tube is submerged within the heattransfer fluid.

According to another exemplary embodiment of the present invention,there is provided a method of circulating a working fluid in a closedloop within a solar air conditioning system, the method includingcompressing the working fluid by squeezing to pack molecules of theworking fluid closer together, heating the compressed working fluidusing radiant energy from the sun, condensing the heated working fluidby cooling and changing a state of the heated working fluid from a gasinto a liquid, and evaporating the condensed working fluid by changing astate of the condensed working fluid from a liquid into a gas.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects of the invention will become apparent andmore readily appreciated from the following description of exemplaryembodiments, taken in conjunction with the accompanying drawings, ofwhich:

FIG. 1 is a block diagram of a related art air conditioning system.

FIG. 2 is a more detailed view of the condenser of the related art airconditioning system of FIG. 1.

FIG. 3 is a more detailed view of the evaporator of the related art airconditioning system of FIG. 1.

FIG. 4 is a block diagram of a solar air conditioning system accordingto an exemplary embodiment of the present invention.

FIG. 5 is a detailed view of a solar collector according to an exemplaryembodiment of the present invention.

FIG. 6 is a cutaway view of the solar collector according to anexemplary embodiment of the present invention.

FIG. 7 is a bottom view of an inner tank of the solar collectoraccording to an exemplary embodiment of the present invention.

FIG. 8 is a detailed view of an evacuated tube according to an exemplaryembodiment of the present invention.

FIG. 9 is a diagram showing the reflectance, absorption and emittancerates of the sunlight entering an evacuated tube, according to anexemplary embodiment of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE PRESENT INVENTION

Reference will now be made in detail to exemplary embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to like elementsthroughout. Exemplary embodiments are described below, in order toexplain the present invention by referring to the figures.

FIG. 4 is a block diagram of a solar air conditioning system (400),according to an exemplary embodiment of the present invention. As shownin FIG. 4, working fluid arrives at the solar compressor (401) as acool, low-pressure gas. The solar compressor (401) is powered byelectricity to mechanically squeeze the working fluid, and the squeezingresults in packing the molecules of the working fluid closer together.The closer the molecules of the working fluid are together, the higherthe working fluid's energy and temperature.

After compression by the solar compressor (401), the working fluidleaves the solar compressor (401) as a hot, high-pressure gas and entersinto a solar collector (402). The solar collector (402) superheats theworking fluid, further increasing the temperature and pressure of theworking fluid. In the solar collector (402), the temperature of theworking fluid is increased by using the energy from the sun's radiation,and this absorbed heat in a closed loop environment produces pressurewhich compresses the working fluid into a superheated gas of highpressure. The working fluid in this state may be in the form of a hightemperature vapor.

The working fluid leaves the solar collector (402) as a superheated gasof high-pressure, and flows into a condenser (403). The gaseous workingfluid enters the condenser (403) and begins cooling and changing backinto a liquid at the very top of the coils of the condenser (403). Thisaccelerated condensation is possible due to the phenomenon thatcondensation, of the working fluid starts to occur quicker at hightemperatures and pressures, and less heat removal is required forcondensation at the higher temperatures and pressures. The highertemperature and pressure, and greater temperature difference between thecoils of the condenser (403) and the ambient temperature, allow for abetter heat exchange throughout the entire system of the solar airconditioning system (400).

In comparison, the temperature difference between the coils of thecondenser (102) of the related art air conditioning system (100) and theambient temperature is smaller, and the gaseous working fluid enteringthe condenser (102) is a lower temperature than the gaseous workingfluid entering the condenser (403), and thus the gaseous working fluidin the condenser (102) only begins cooling and Changing back into aliquid at the bottom one-third of the coils of the condenser (102) inthe related art air conditioning system (100). In the solar airconditioning system (400), the entire coil face of the condenser (403)is utilized in the condensing process, allowing for better heat exchangethroughout the entire system.

When the working fluid leaves the condenser (403) as a semi-liquid, itstemperature is much cooler and its state has changed from a gas to aliquid under high pressure. The working fluid leaving the condenser(403) is in a subcooled liquid state under compression. In the solar airconditioning system (400), because the working fluid is superheated bythe solar collector (402), the working fluid is in a hotter,higher-pressured gas state when entering the condenser (403), and thusleaves the condenser (403) in a colder and more liquid state as comparedto the process in the related art air conditioning system (100). Due tothe increased temperature difference between the working fluid enteringthe condenser (403) and the ambient temperature, heat exchange isimproved throughout the entire system of the solar air conditioningsystem (400), more of the working fluid is changed from a gas to aliquid by the condenser (403), and the colder and more liquidous stateof the working fluid entering the evaporator (405) enables more heat andhumidity to be removed in the evaporation process. For example, a 5° F.increase in temperature of the working fluid entering the condenser(403) results in approximately 20% more humidity removal in the solarair conditioning system (400).

In addition, the temperature of the working fluid leaving the evaporator(405) and entering the solar compressor (401) also becomes colder ascompared to the temperature of the working fluid at the inlet of thecompressor (101) of the related art air conditioning system (100). Thisis because the working fluid enters the evaporator (405) in the colderand more liquidous state.

Furthermore, the additional heating of the working fluid by the solarcollector (402) reduces the work done by the solar compressor (401),such that the more energy the solar collector (402) transfers to theworking fluid, the less the solar compressor (401) needs to work.

The working fluid in the liquidous state is then sent into an evaporator(405) through a metering device (404) that controls the dispensing rateof the subcooled working fluid to the evaporator (405). The meteringdevice (404) may be any device that reduces and controls the pressure ofthe working fluid, such as a thermostatic expansion valve. Within theevaporator (405), the liquid's pressure drops further and the liquidbegins to evaporate into a gas because the ambient temperature is higherthan the working fluid's boiling temperature. As the liquid changes togas and evaporates, heat is extracted from the surrounding air. Thisheat is needed for separating the molecules of the working fluid in itstransformation of state from subcooled semi-liquid to gas. By the timethe working fluid leaves the evaporator (405), it is a cool,low-pressure gas. The working fluid then returns to the solar compressor(401) as the cool, low-pressure gas to begin this cycle all over again.

By having two sources of heat and pressure (i.e., the solar compressor(401) and the solar collector (402)), more working fluid is presentwithin the solar air conditioning system (400) as compared to therelated art air conditioning system (100). The additional working fluidis added to fill the volume within the pipes and tubes of the solarcollector (402). In the related art air conditioning system (100), thesystem is charged (i.e., the proper amount of working fluid refrigerantis added to the system) by using the superheat and subcooling methods.However, instead of superheat and subcooling, the solar air conditioningsystem (400) may be charged using the ideal gas law, in which the stateof an amount of gas is determined by its pressure, volume andtemperature, that is, PV=nRT, where P is the pressure of the workingfluid (e.g., in units of psi), V is the volume of the sealed spacewithin which the working fluid circulates, n is the amount of workingfluid, R is the universal gas constant, and T is the temperature. Thesolar air conditioning system (400) is correctly charged once thepressure is balanced in accordance with the two sources of heat andpressure (i.e., with the solar compressor (401) and the solar collector(402)) and the total working fluid volume to equal the desired chargetemperature. The pressure P may be measured from a point on thehigh-pressure side of the solar air conditioning system (400), that is,between the solar collector (402) and the condenser (403). As such, thetemperature at the input of the condenser (403) can be controlled basedon the setting of the pressure P (psi) of the working fluid at thehigh-pressure side.

When charging the solar air conditioning system (400), a psi chargingtable may be used. This psi charging table specifies the desired psipressure of the working fluid at varying ambient temperatures, with thevalues of the psi charging table varying based on the working fluidbeing used. Accordingly, in an exemplary embodiment of the presentinvention, the solar air conditioning system (400) may be charged suchthat the pressure of the working fluid at the high-pressure side is setaccording to the psi charging table corresponding to the type of workingfluid being used.

According to an exemplary embodiment of the present invention, thevolume of working fluid in the solar air conditioning system (400),after proper charging, is larger than the volume of working fluid in therelated art air conditioning system (100), as additional working fluidis required in order to fill the additional volume of piping and tubingadded to the system due to the addition of the solar collector (402).This additional volume of working fluid is free fuel for heat removal,without having increased the capacity or the energy consumption of thecompressor (401). The increased volume of working fluid in the solar airconditioning system (400) enables more heat removal when the system isin operation. The volume of working fluid present in the solar airconditioning system (400) according to an exemplary embodiment of thepresent invention may be significantly more than the volume of workingfluid present in the related art air conditioning system (100).

Furthermore, although the solar air conditioning system (400) contains alarger volume of working fluid as compared to that of the related artair conditioning system (100), the working fluid in the solar airconditioning system (400) is under lower pressure, reducing the energyrequired by the solar compressor (401) to compress the working fluid.

FIG. 5 depicts the solar collector (402) in more detail, according to anexemplary embodiment of the present invention. As shown in FIG. 5, thesolar collector (402) includes a plurality of evacuated tubes (501). Aninlet pipe (502) receives the working fluid from the solar compressor(401), and the working fluid enters u-tubes (503) of each of therespective evacuated tubes (501). The working fluid travels from theinlet pipe (502) down through the u-tubes (503) within the evacuatedtubes (501), becoming superheated in this process, and then circulatesback out as a hotter gas which is then sent into an outlet pipe (504).The inlet pipe (502) and the outlet pipe (504) may be copper tubing ofabout one-half inch in diameter, but is not limited thereto, and theu-tubes (503) may be copper tubing of about three-eights inch indiameter, but is also not limited thereto.

By utilizing both the solar compressor (401) and the solar collector(402) in the solar air conditioning system (400), the load of heatingthe working fluid is shared between these two components (i.e., thesolar compressor (401) and the solar collector (402)) depending on theamount of available solar energy. The load on and work done by the solarcompressor (401) may be reduced using the free energy (i.e., solarenergy utilized by the solar collector (402)) to increase thetemperature delivered to the top of the coils in the condenser (403),and more heat removal (BTUs) capability is added via the additionalvolume of working fluid present in the solar air conditioning system(400).

According to an exemplary embodiment of the present invention, the inletpipe (502), the outlet pipe (504), and upper portions of the u-tubes(503) and evacuated tubes (501) may be encased by an outer housing(505).

FIG. 6 is a cutaway view of the solar collector (402) according to anexemplary embodiment of the present invention. As shown in FIG. 6, aninner tank (607) is provided within the outer housing (505). The innertank (607) further encloses the inlet pipe (502), the outlet pipe (504),and upper portions of the u-tubes (503) and evacuated tubes (501). Theinner tank (607) may be filled with a heat transfer fluid (608) andconfigured to seal the heat transfer fluid (608) within, such that theheat transfer fluid (608) fills an interior space so as to surround theinlet pipe (502), the outlet pipe (504), and the u-tubes (503), and alsofills the evacuated tubes (501).

According to an exemplary embodiment of the present invention, the innertank (607) may be insulated using a material such as rock wool, but isnot limited thereto, with insulation (606) filling a space between theinner tank (607) and the outer housing (505). Also, the heat transferfluid (608) may be injected into the inner tank (607) by way of a heattransfer fluid fill hole (609).

FIG. 7 is a bottom view of the inner tank (607), according to anexemplary embodiment of the present invention. As shown in FIG. 7, theinner tank (607) includes holes (501) from which the u-tubes (503)extend out from the inlet pipe (502) and outlet pipe (504), and alsothrough which the upper portion of the evacuated tubes (501) areinserted. The upper portions of the evacuated tubes (501) are the openended sides of the evacuated tubes (501), and are inserted into theholes (501) and sealed by sealant rings (701). Upon injecting the heattransfer fluid (608) into the inner tank (607) by way of the heattransfer fluid fill hole (609), the heat transfer fluid (608) thus alsofreely enters and fills each of the evacuated tubes (501) as well assurrounds the u-tubes (503) and the inlet pipe (502) and outlet pipe(504).

In an exemplary embodiment of the present invention, the solar collector(402) may further include heat transfer fins (not shown) welded to aportion of each of the u-tubes (503). The heat transfer fins may circleand make contact with an inner glass tube (802) (see FIG. 8) of theevacuated tubes (501), or make contact with a selective coating ofAl—N/Al applied to the inner glass tube (802) of the evacuated tubes(501). The heat transfer fins may be formed of a metal, such asaluminum, or any other substance with good heat transfercharacteristics.

The heat transfer fluid (608) has a high boiling point, preferably atleast 424° F., and more preferably between 525° F. and 800° F. Theu-tubes (503) are immersed within the heat transfer fluid (608) enablinghigher heat transfer efficiency. Heat from solar energy is transferredby the heat transfer fluid (608) through to the u-tubes (503), so as tosuperheat the working fluid flowing through the u-tubes (503).

According to an exemplary embodiment of the present invention, anynumber of evacuated tubes (501) may be used in constructing the solarcollector (402). The larger the number of evacuated tubes (501), themore energy that may be collected and transferred to the working fluid.Also, the diameter and length of the evacuated tubes (501) may each bevaried, with a larger surface area generally leading to more energytransferred to the working fluid within the u-tubes (503).

FIG. 8 is a detailed view of the evacuated tube (501) according to anexemplary embodiment of the present invention. As shown in FIG. 8, theevacuated tube (501) is constructed as a double wall vacuum tube with atriple deposition selective surface coating. The evacuated tube (501)may be formed from two concentric transparent borosilicate glass tubes(Pyrex®), with the inner glass tube (802) that may be coated with theselective coating of Al—N/Al which absorbs and converts solar radiationand infrared light into heat while reducing emissivity. A barium getteris used at the bottom of the inner glass tube (802) and actively absorbsall CO, CO², N², O², and H²O. The evacuated tube (501) may be formed asone continuous piece of glass.

Between the inner glass tube (802) and an outer glass tube (803), amultiple deposition selective surface may be formed to absorb the fullvisible and infrared light radiation wavelengths from 0.3 to 1.3μ. Afirst deposition layer (804) of the multiple deposition selectivesurface is a copper metal layer M-AL—N/CU which has a low emission ratioand a high thermal transmission through the inner glass tube (802) tothe respective u-tube (503).

The multiple deposition selective surface includes a second depositionlayer (805) of AL²O³ film to prevent cross migration. This entrainmentallows the copper molecular layer (first deposition layer (804)) to bevery stable at temperatures in excess of 750° F.

The multiple deposition selective surface also includes a thirddeposition layer (806) of a cermet aluminum nitride AL—N/M-AL—N,produced by sputtering simultaneously in a gas mixture of argon andnitrogen. The third deposition layer (806) absorbs solar radiation atvery low emissivity (e.g., e=5%).

In another exemplary embodiment of the present invention, the heattransfer fluid (608) may include a chemical composition enablingabsorption of the energy from the sun's radiation and converting thisenergy into heat. In a further exemplary embodiment of the presentinvention, evacuated tubes (501) may be provided without the Al—N/Alselective coating on the inner glass tube (802).

FIG. 9 is a diagram showing the reflectance, absorption and emittancerates of the sunlight entering the evacuated tube (501) according to anexemplary embodiment of the present invention. As shown in FIG. 8, thesunlight strikes the outer glass tube (803), and of the sunlightstriking the outer glass tube (803), 6.3% is reflected and 1.8% isabsorbed, leaving 91.9% of the sunlight to strike the inner glass tube(802). Of the 91.9% of the sunlight striking the inner glass tube (802),another 6.3% is reflected and 4.4% is emitted due to coating emittance,leaving 81.2% of the sunlight to pass through to the inside of theevacuated tube (501).

When the evacuated tubes (501) receive solar radiation, the evacuatedtubes (501) with their triple deposition selective surface coatingenables heat to be generated and collected. This heat is transferred bythe heat transfer fluid to the u-tubes (503) and absorbed by the workingfluid flowing through the u-tubes (503). In such a way, the workingfluid may be superheated before being provided to the condenser (403).The higher temperature of the working fluid entering the condenser (403)allows for a higher percentage of heat transfer due to the increase ofΔT between the superheated working fluid temperature and the outsideambient air temperature.

The foregoing exemplary embodiments and advantages are merely exemplaryand are not to be construed as limiting the present invention. Thepresent teaching can be readily applied to other types of apparatuses.Also, the description of exemplary embodiments of the present inventionis intended to be illustrative, and not to limit the scope of theclaims, and many alternatives, modifications, and variations will beapparent to those skilled in the art.

What is claimed is:
 1. A cooling system comprising: a compressorconfigured to compress a working fluid; a solar collector coupled tosaid compressor, said solar collector configured to heat said workingfluid to convert said working fluid into a gaseous state; a condensercoupled to said solar collector, said condenser configured to condensesaid heated working fluid; and an evaporator coupled between saidcondenser and said compressor, said evaporator configured to evaporatesaid condensed working fluid, wherein said solar collector comprises: atleast one evacuated tube configured to heat said working fluid, whereinsaid working fluid is heated while present within an interior space ofsaid at least one evacuated tube.
 2. The cooling system of claim 1,wherein said solar collector heats said working fluid using radiantenergy from the sun.
 3. The cooling system of claim 1, wherein saidsolar collector further comprises: an inlet pipe that receives saidworking fluid; at least one u-tube that is configured to receive at afirst end said working fluid from said inlet pipe; an outlet pipe thatis configured to receive said working fluid from a second end of said atleast one u-tube, wherein said at least one u-tube is further configuredto extend within the interior space of said at least one evacuated tube.4. The cooling system of claim 3, wherein said solar collector comprisesa plurality of u-tubes and a plurality of evacuated tubes, wherein eachu-tube of said plurality of u-tubes is configured to receive saidworking fluid from said inlet pipe, and wherein each u-tube of saidplurality of u-tubes is further configured to extend within acorresponding evacuated tube of said plurality of evacuated tubes. 5.The cooling system of claim 4, wherein said working fluid flows fromsaid inlet pipe into said first end of said at least one u-tube andexits said at least one u-tube from said second end and flows into saidoutlet pipe.
 6. The cooling system of claim 3, wherein said workingfluid travels through said at least one u-tube, is heated using radiantenergy collected by said evacuated tubes, then circulates out from saidat least one u-tube in the superheated gaseous state, and is thendelivered into said outlet pipe.
 7. The cooling system of claim 3,wherein said solar collector further comprises an inner tank, andwherein said inlet pipe and said outlet pipe are housed within saidinner tank.
 8. The cooling system of claim 7, wherein said inner tankcomprises at least one hole through which said at least one u-tubeextends out from said inlet pipe and said outlet pipe, and wherein anupper portion of an open ended side of said at least one evacuated tubeis inserted into said at least one hole.
 9. The cooling system of claim8, wherein said inner tank and the interior space of said at least oneevacuated tube is filled with a heat transfer fluid, wherein said atleast one u-tube is submerged in said heat transfer fluid, and whereinsaid heat transfer fluid is sealed within an enclosure formed of saidinner tank in combination with said at least one evacuated tube insertedinto said at least one hole of said inner tank.
 10. The cooling systemof claim 7, wherein said solar collector further comprises: aninsulating material that surrounds said inner tank; and an outer housingthat encloses said inner tank and said insulating material.
 11. Thecooling system of claim 3, wherein said solar collector furthercomprises a heat transfer fluid that fills the interior space of said atleast one evacuated tube and within which said at least one u-tube issubmerged.
 12. The cooling system of claim 11, wherein said heattransfer fluid absorbs radiant energy from the sun, converts the radiantenergy into heat, and transfers the heat to said working fluid.
 13. Thecooling system of claim 12, wherein said heat transfer fluid has aboiling point of at least 424° F.
 14. The cooling system of claim 3,wherein said solar collector further comprises at least one heattransfer fin attached to a portion of said at least one u-tube.
 15. Thecooling system of claim 14, wherein said at least one heat transfer fincontacts an inside wall of said at least one evacuated tube.
 16. Thecooling system of claim 14, wherein said at least one heat transfer finprotrudes from said at least one u-tube and contacts a selective coatingapplied to an inner surface of said at least one evacuated tube.
 17. Thecooling system of claim 16, wherein said selective coating comprisesAl—N/AL and enables said at least one evacuated tube to absorb andconvert radiant energy into heat.
 18. The cooling system of claim 1,wherein said at least one evacuated tube is a double wall vacuum tubecomprising a triple deposition selective surface coating.
 19. Thecooling system of claim 1, wherein said at least one evacuated tubereceives radiant energy from the sun, generates heat from the radiantenergy, and transfers the heat through a heat transfer fluid to saidworking fluid flowing within the interior space of said at least oneevacuated tube.
 20. A method of circulating a working fluid in a closedloop within a cooling system, the method comprising: compressing saidworking fluid by applying pressure to said working fluid to packmolecules of said working fluid closer together; heating said compressedworking fluid using radiant energy from the sun, wherein said compressedworking fluid is heated within an evacuated tube that converts theradiant energy into heat for heating said compressed working fluid whilesaid working fluid is present within an interior space of said evacuatedtube; condensing said heated working fluid by cooling and changing astate of said heated working fluid from a gas into a liquid; andevaporating said condensed working fluid by changing a state of saidcondensed working fluid from a liquid into a gas.